The invention concerns an X-ray optical element with a Soller slit comprising several lamellas for collimating an X-ray beam with respect to the direction of the axis of the Soller slit, and with a further collimator for delimiting an X-ray beam, wherein the further collimator is rigidly connected to the Soller slit during operation.
X-ray diffractometry can be used for various analytical tasks, for which different measuring geometries are used, e.g. Bragg-Brentano or parallel beam geometry. However, different optical elements are required in the optical path for this purpose. In order to permit fast change between the different measuring geometries, it is desired to minimize the necessary modifications.
U.S. Pat. No. 6,807,251 B2 discloses an X-ray diffractometer with a parabolic mirror for use of the diffractometer in parallel beam geometry, and a slit collimator for delimiting the X-ray beam in the Bragg Brentano geometry. The mirror and the slit collimator are rigidly connected to each other. A rotatable path selection disc having a slit is disposed behind the aperture/mirror unit, through rotation of which the X-ray beam (parallel or divergent) required for the corresponding geometry can be selected.
U.S. Pat. No. 6,665,372 B2 discloses an X-ray diffractometer, in which the X-ray radiation can be guided in sections along different beam paths for different tasks, wherein one beam path extends in a straight line through a collimator system having adjustable and/or exchangeable collimators, from the sample to the X-ray detector, while the other beam path has a bend and extends initially from the sample position to a dispersive or reflecting X-ray optical element, and from there to the X-ray detector. The bent beam path can be collimated out with respect to the detector by means of a shutter collimator. The collimator and the dispersive or reflecting X-ray optical element are rigidly aligned with respect to each other and can be pivoted together with respect to the sample.
These arrangements are disadvantageous in that the X-ray beam is divided and for this reason, only part of the radiation emitted by the X-ray source can be used for each application. Moreover, the conventional arrangements require a relatively large amount of space in order to be able to realize the various beam paths.
In particular, for measurements in parallel beam geometry, the use of Soller slits is advantageous to delimit vertical and/or horizontal divergences of X-rays. Linear Soller slits are described in detail e.g. in U.S. Pat. No. 6,266,382 B1, US2005/0281382 A1 and U.S. Pat. No. 6,307,917 B1.
Bruker Advanced X-ray solutions “Diffraction Solutions D8 Advance” 2002 discloses an X-ray diffractometer for reflection and transmission measurements in parallel beam geometry. The X-ray beam emitted by the sample thereby extends through a linear or a radial Soller slit.
U.S. Pat. No. 6,307,917 B1 discloses an X-ray apparatus with Soller slit for collimating divergent X-rays. The Soller slit is part of a monochromator unit with a monochromator collimator, which is used to delimit the X-ray beam that is subsequently collimated by the Soller slit.
It is the object of the invention to propose an X-ray optical element with a Soller slit and a further collimator, which enables automatic change between the Soller slit and the further collimator.